The present invention relates generally to communication systems, and more specifically to improved methods and arrangements for reducing unnecessary signaling and processing that can occur within mobile communications networks that employ call optimization techniques.
There has long been a need to provide reliable and cost-efficient communications around the world. This need has traditionally has been addressed by installing terrestrial communication networks and providing satellite connectivity within and/or between the various terrestrial communication networks when necessary. In such a communication system there is usually at least one optimal route available for completing a communication or call. An optimal routing of the call, from the subscriber""s unit to an end destination, may require the allocation of several different terrestrial and/or satellite network resources. It is typically preferred that such calls be established and maintained through those resources that are best positioned/configured to provide the desired level of service at an optimal cost to the service provider. As such, calling optimization techniques are often employed to efficiently utilize the network resources.
With recent increased demand for mobile communications, such as cellular radio-based telecommunications, the need to provide call optimization has increased dramatically. This is especially true for mobile telecommunication networks that include hundreds or thousands of network resources, including ground stations and satellites.
With this in mind, FIG. 1 is a block diagram depicting a portion of a conventional communications system 10 that is configured to optimize a call from a mobile station through either satellite resources and/or available terrestrial resources.
Communications system 10 as depicted in FIG. 1 and described herein is not intended to provide a exhaustive description of such a communications system. Providing such a description is beyond the scope of the present invention. Instead, communications system 10 is provided to focus on specific problems associated with such a system and certain types of optimization techniques that are used therein to allocate resources. For a more complete description of such an exemplary communications system and related optimization techniques see co-pending U.S. patent application Ser. No. 08/996,480 filed Dec. 23, 1997, which is hereby incorporated by reference.
Referring again to FIG. 1, communications system 10 includes a satellite-configured mobile communications network 12 and a switched network 14. While switched network 14 is typically a public switched telephone network (PSTN) that is configured to provide further communications services, in certain arrangements switched network 14 can be any type of communications network and need not actually be a xe2x80x9cswitched networkxe2x80x9d.
Within mobile communications network 12 there is shown a mobile station (MS) 16, a base station system (BSS) 18 and a switching system (SS) 20. Mobile station (MS) 16 typically includes a mobile radio terminal, such as, for example, a car phone or other portable phone or data communication device that is used by mobile subscribers.
Mobile station (MS) 16 is configured to communicate through radio frequency (RF) signals with a base transceiver station (BTS) 22 and base station controller (BSC) 24 within base station system (BSS) 18.
In turn, base station system (BSS) 18 is connected to a combined mobile switching services switching center/visitor location register (MSC/VLR) 26 within switching system (SS) 20. Typically, several base station systems (BSSs) are served by a single MSC/VLR. MSC/VLR 26 essentially controls calls to and from other telephony and data communication systems. The visitor location register (VLR) within MSC/VLR 26 usually includes a data base containing information about each mobile station (MS) currently located within the area served by the MSC/VLR 26.
As depicted, in addition to communicating with mobile station (MS) 16, base station system (BSS) 18 is also configured to communicate to at least one similarly configured MSC/VLR 30 via a satellite 28. Typically, although not necessary, satellite 28 is in a geosynchronous orbit and is capable of supporting communications over a large geographical region.
The exemplary optimization techniques described herein are typically employed to support the determination as to whether it would be more advantageous to complete a mobile station related call through either a substantially terrestrial route or a satellite-assisted route.
To understand how such optimization techniques are used, it is important to understand the basic subscriber registration functions performed within mobile communications network 12. To utilize mobile communication network 12, mobile station (MS) 16 needs to register with MSC/VLR 26. Typically, a registration process occurs when mobile station (MS) 16 is activated within or enters the coverage area of network 12, and more specifically when mobile station (MS) 16 is within the coverage area supported by a MSC/VLR.
To support the registration process, a home location register (HLR) 32 is provided within switched system (SS) 20. Home location register (HLR) 32 is connected to each MSC/VLR and contains subscriber information with respect to each subscribed mobile station (MS). As mobile station (MS) 16, for example, moves within the coverage area of mobile communications network 12, mobile station (MS) 16 registers with each successive MSC/VLR. Upon registration, each MSC/VLR requests information about mobile station (MS) 16, and, in doing so, also provides updated location information to HLR 32. In this manner, home location register (HLR) 32 and the current MSC/VLR are made aware of the location of mobile station (MS) 16, and the current MSC/VLR is provided subscriber information about mobile station (MS) 16.
When a call optimization technique is employed, there may be a need for the mobile station (MS) 16 to register with a more optimal MSC/VLR, such as, for example, registering with MSC/VLR 26 to utilize base station system (BSS) 18 and satellite 28. In this example, a call optimizer 34 is included within mobile communications network 12 to analyze a called party number that is included within the Access Request message transmitted by mobile station (MS) 16 over a Random Access Channel (RACH). Call optimizer 34 can be a separate block (as shown), or otherwise can be included within BSS 18, MSC/VLR 26, and/or HLR 32.
Call optimizer 34 determines if a more optimal MSC/VLR for the mobile originated call. Based on this determination, mobile station (MS) 16 may be required to xe2x80x9cre-registerxe2x80x9d with a more optimal MSC/VLR.
One of the problems with this exemplary call optimization process arises when mobile station (MS) 16 is barred from making certain types or all types of outgoing calls based on the type of subscribed service. By way of example, a subscriber may be barred under his or her subscriber service contract from making international calls. When an attempt is made to place such a barred call, the call optimizer 34 may determine that re-registration of mobile station (MS) 16 is required to optimize the call. This re-registration process requires additional signaling and processing to occur within mobile communications network 12, and more specifically, for example, between and within the MSC/VLR 26 (i.e., the optimal MSC/VLR) and HLR 32.
Once this re-registration process has been completed, then MSC/VLR 26 attempts to complete the call, only to determine that the call is barred. Mobile station (MS) 16 will then need to be re-registered again with the original MSC/VLR following this failed call attempt.
By way of additional example, a subscriber that initiates a non-barred call and then hangs up, may also impact the mobile communications network 12 by initiating call optimization processes that result in unnecessary re-registering of mobile station (MS) 16. Given these scenarios, it is possible that one or more subscribers could intentionally or unintentionally cause an extensive amount of unwanted signaling and processing to occur within mobile communications network 12 by repeatedly, continually, and/or simultaneously initiating calls (but not completing) that require call optimization processes that result in the re-registration of the mobile station (MS) 16 and/or additional reallocation of resources.
Thus, there is a need for methods and arrangements that are more robust and effectively reduce the possibility that either intentional or unintentional use might lead to excessive signaling and processing within a mobile communications network that is configured to optimize calls and in doing so reallocate network resources.
The present invention provides methods and arrangements that are more robust and effectively reduce the possibility that either intentional or unintentional use might lead to excessive signaling and processing within a mobile communications network that is configured to optimize calls and in doing so reallocates network resources. For example, in accordance with certain aspects of the present invention, the methods and arrangements prevent such activity by identifying potential abuses, and providing controlling mechanisms within the mobile communications network that monitor and control re-registration and subsequent access request to the networks resources.
Thus, the above stated needs and others are met by an arrangement that includes a mobile station that is configured to selectively attempt to register with at least one xe2x80x9cgatewayxe2x80x9d within a mobile communications network, and logic arranged to prohibit the mobile station from using the gateway for a period of time following a rejected attempt to register with the at least one base station. In certain embodiments, the logic is located within the mobile station and actively disables the mobile station from initiating selected calls during the period of time. In other embodiments the logic is located within the mobile station and disables the mobile station from initiating a location updating request during a subsequent attempt to register with the base station during the period of time. The logic, in accordance with still further embodiments, can be located within a base station subsystem where it actively disables support for selected calls from the mobile station during the period of time. This period of time, is essentially a pre-defined or dynamically programmed back-off time that can significantly prevent abuse to the mobile communications network resources.
A mobile communication system is also provided to address the above stated needs. In accordance with certain exemplary embodiments, the system includes at least one mobile station, a master controller containing subscriber information about the mobile station, and a first base station subsystem and a second base station subsystem, each of which is configured to receive the subscriber information from the master controller when the mobile station registers with the respective xe2x80x9cgatewayxe2x80x9d and to process call requests originated from the mobile station when registered with the first base station subsystem. The system further includes a call optimizer that is at least partially within the first base station subsystem and configured to support processing of call requests from the mobile station. Based on a called party number in the call request received from the mobile station. The call optimizer is also configured to direct that the mobile station attempt to register or re-register with the second base station subsystem as a function of the called party number. For example, the second base station subsystem may be the optimal gateway for a given call. To prevent abuse to the systems resources, the system further includes a back-off timer that configured to prohibit the mobile station from using the second base station subsystem for a period of time following a rejected attempt to register with the second base station.
Additional control is provided within the system, in accordance with still further embodiments of the present invention, by configuring the master controller to count a number of rejected attempts by the mobile station over a first duration of time, and reject the mobile stations subsequent attempts to register with the second base station subsystem or gateway during a second duration of time if the number of rejected attempts is greater than a threshold value.
The above stated needs are also met by various methods for use in a mobile communications network that is configured to provide call optimization by re-registering a mobile station with a subsequent gateway. Here, in accordance with certain embodiments of the present invention, the method includes the steps of identifying when a mobile station is attempting to register with a subsequent gateway in response to a call optimization determination, and prohibiting the mobile station from using the subsequent gateway for a period of time following a failed registration attempt.